Valves of this type are especially well suited for regulating and shutting off the liquid flow in conduits at extremely high liquid pressures. Thus, such valves are advantageously used in feed water conduits of nuclear reactors, where the pressure of the water often amounts to 25 bar or more. An important advantage of the valve arrangement described is that the reciprocating piston can be rapidly and accurately moved to its closing position also at extremely high liquid pressures. This is due to the fact that the piston moves perpendicularly to the liquid jets entering radially through the cylinder-tube holes and successively closes the holes. Thus, the setting mechanism will not be exposed to the full force of the liquid rushing through the conduit at high pressures.
An inconvenience of such prior-art valves is, however, that the valve housing as well as the associated conduits tend to be set in vibration. Under unfavourable circumstances, the vibrations may attain an amplitude of 1 mm or more, and thus be particularly difficult to overcome. The vibrations are caused by a number of concurrent factors, the most important being that the part flows formed when the water jets coming through the cylinder-tube holes and impinging upon the walls of the distributing means, are dispersed not only directly towards the outlet member of the valve housing, but also towards the body of the piston. Thus, the piston will be acted upon by comparatively important forces from the part flows with which it comes into contact, and the piston and the associated spindle may then be set in self-oscillation. If the oscillations in the piston are intensified and propagated to the conduit system, it may become necessary to close the valve and put it out of use temporarily.
In prior-art valves, efforts have been made to avoid that the water part flows directed towards the body member of the piston come into direct contact with this member. More precisely, a simple plate has been provided at the distributing-means end facing the body member of the piston. Thus, the part flows impinge upon this plate before-reaching the body member of the piston. However, this simple plate cannot prevent the disintegrated water from impinging upon the cylindrical member of the piston, thus subjecting the latter to comparatively important forces. Neither does the plate prevent water from rushing in between the distributing means and the body member of the piston.